Over the years, various proposals have been made for electric powered vehicles. To date, for a number of reasons, electric vehicle systems have yet to become commercial for urban and highway applications.
There have been proposals to employ zinc/air batteries for urban vehicle propulsion. An example is the following publication:
Improved slurry zinc/air systems as batteries for urban vehicle propulsion, by P. C. Foller, Journal of Applied Electrochemistry 16 (1986), 527-543.
Metal/air battery structures are described in the following publications:
U.S. Pat. No. 4,842,963, entitled Zinc Electrode and Rechargeable Zinc-Air Battery;
U.S. Pat. No. 4,147,839, entitled Electrochemical Cell with Stirred Slurry;
U.S. Pat. No. 4,908,281, entitled Metal/air Battery with Recirculating Electrolyte;
U.S. Pat. No. 3,847,671, entitled Hydraulically-Refuelable Metal-Gas Depolarized Battery System;
U.S. Pat. No. 3,716,413, entitled Rechargeable Electrochemical Power Supply;
U.S. Pat. No. 4,925,744, entitled Primary Aluminum-Air Battery;
U.S. Pat. No. 4,341,847, which describes an electrochemical generator having two sedimentation-bed chambers fed in series with an electrolyte which contains particles; and
U.S. Pat. No. 4,719,156, which describes a power storage system employing an aluminum-air cell in which solid discharge products are formed. The system includes means for recirculating electrolyte from the cell so as to flush out the solid discharge products therein. This is achieved by use of a precipitation chamber employing an impeller. Discharge product-free electrolyte is thereafter returned to the cell.
Electrical energy storage systems are described in the following publications:
U.S. Pat. No. 4,843,251 entitled Energy Storage and Supply Recirculating Electrolyte;
Energy on Call by John A. Casazza et al, IEEE Spectrum June, 1976, pp 44-47.
U.S. Pat. No. 4,275,310, entitled Peak Power Generation;
U.S. Pat. No. 4,124,805, entitled Pollution-Free Power Generating and Peak Power Load Shaving System; and
U.S. Pat. No. 4,797,566, entitled Energy Storing Apparatus.
Zinc-air batteries using a replaceable slurry are known. These obviate the problem of dendrite formation in batteries with bifunctional electrodes.
Among disadvantages inherent in zinc-air batteries, however, is that the functional life and ease of rechargeability employing thereof is limited, due to the formation of non-electrically conductive zinc oxide within the slurry, upon electrical discharge thereof.
Further system problems that occur with metal-air systems in general, are the generation thereby of excess heat, and the drying out of the metal-based electrolytic slurry.
The following references describe zinc-air power storage systems including a zinc anode, an air electrode, and means for circulating an electrolyte liquid:
U.S. Pat. No. 3,359,136 entitled Rechargeable Energy Conversion System;
U.S. Pat. No. 3,505,113 entitled Rechargeable Energy Conversion Process;
U.S. Pat. No. 3,708,345 entitled Electrochemical Energy Conversion System. This reference also teaches the use of a jet pump so as to scour zinc oxide discharge deposits from the anode.
U.S. Pat. No. 3,666,561 entitled Electrolyte Circulating Battery;
U.S. Pat. No. 4,842,963 entitled Zinc Electrode And Rechargeable Zinc-Air Battery. The described battery is electrically rechargeable and also includes means for filtering zinc oxide discharge products accumulating in the circulating electrolyte. Zinc is plated out during recharging of the battery.
The following reference describe zinc-air power storage systems employing a continuously circulated slurry of zinc powder suspended in an electrolyte:
U.S. Pat. No. 3,977,903 entitled Forced-Flow Electrochemical battery;
U.S. Pat. No. 4,038,458 entitled Zinc-Air Electrochemical Cell;
U.S. Pat. No. 4,126,733 entitled Electrochemical Generator Comprising An Electrode In The Form Of A Suspension;
U.S. Pat. No. 4,341,847 entitled Electrochemical Zinc-Oxygen Cell; and
U.S. Pat. No. 3,887,400 entitled Method And Apparatus For Electrochemically Producing An Electrical Current.
A disadvantage inherent in above-listed patents describing the continuous recirculation of a zinc-containing electrolyte slurry is that, in order to provide a power storage system of sufficient capacity to power a vehicle, the overall weight of such a system would be so large and heavy as to render its use impractical.
A further publication teaching the continuous circulation of a slurry of zinc powder and electrolyte is U.S. Pat. No. 3,981,747, entitled Process For Producing Electric Current By The Electrochemical Oxidation Of An Active Anodic Metal, Especially Zinc. Although this reference specifically teaches that continuous re-circulation of zinc particles and electrolyte slurry does not in itself prevent passivation of the zinc during discharge, the system described in this reference is, nonetheless, based on a continuous circulation of such a slurry, but wherein the precipitation of discharged zincate from solution is provided by the addition of a lightweight material, such as aluminum.
The following additional references are also noted:
U.S. Pat. No. 3,520,728 entitled Electrical Accumulator With A Metal Hydride Serving As The Cathodic Reactive Material Arranged In Suspension In The Electrolyte describes a slurry of metal hydride particles and an electrolyte which flows through an electrochemical cell.
U.S. Pat. No. 3,554,810 entitled Metal-Oxygen Power Source describes a metal-air power source with a reversibly collapsible electrolyte storage means.
U.S. Pat. No. 4,005,061 is directed to a method of recovering potassium hydroxide and zinc oxide from potassium zincate solutions by the addition thereto of an organic solvent.
U.S. Pat. No. 4,283,466 is directed to a process for chemical reaction using flowing slurry.
U.S. Pat. No. 4,521,497 describes an electrically rechargeable zinc-air battery having electrodes which are rotated so as to control dendrite growth.
The teachings of the foregoing publications are incorporated herein by reference.